This is an example program that actually allows the car to race using the FRDM-TFC library!

Dependencies:   FRDM-TFC

Fork of TFC-RACING-DEMO by Daniel Hadad


This is an example program that uses the FRDM-TFC library to actually permit a car using the FDRM-TFC shield + FRDM-KL25Z to race around a center line track.

Exercises designed for Mentoring Matters Car Summer Camp for Summer 2014 at Freescale, Inc. in Austin, Texas


5 MODES OR EXERCISES THAT WILL ALIGN WITH DIP SWITCH SETTINGS IN BINARY FASHION e.g. Mode 1 = 001 = switch 1 is on, switch 2 is off, switch 3 is off

0 = 000 = Garage Mode, button light test to see if car alive!!

  • PUSHBUTTON A - Light LEDs 0 and 1
  • PUSHBUTTON B - Light LEDs 2 and 3
  • (switch 4 does nothing)

1 = 001 = Garage Mode, forward/reverse adjust, no auto steer, terminal output

  • POT 1 - Controls speed of right wheel: CCW = reverse; CW = forward
  • POT 2 - Controls speed of left wheel: CCW = reverse; CW = forward
  • NOTE In this mode the high pitched whine heard is of the H-bridge being active. To disable whine, briefly put into demo mode 1 above.
  • (switch 4 does nothing)

2 = 010 = Garage Mode, steering adjust, no auto steer, terminal output

  • POT 1 - Controls Servo: CCW = left; CW = right
  • (switch 4 does nothing)

3 = 011 = Garage Mode, Camera test, some auto steer, terminal output

  • switch 4 : OFF = normal dec data, ON = o-scope mode

4 = 100 = Track Mode, Auto Steer, safe settings

  • LIGHT SPEED = 0.4 default
  • switch 4 = terminal output on/off
  • Pot0 = controls motor speed
  • Pot1 = controls value to multiply with Kp for proportional control

5 = 101 = Track Mode, Auto Steer, fast settings

  • LUDICROUS SPEED = 0.6 default
  • switch 4 = terminal output on/off
  • Pot0 = controls motor speed
  • Pot1 = controls value to multiply with Kp for proportional control

6 = 110 = future upgrades

7 = 111 = future upgrades

Car Hookup


  • Code written assuming left motor hooked to B1(red)/B2(black) and right motor hooked to A1(red)/A2(black).


  • Be sure to hook positive (red) to 'Vbat' and negative (black) to 'Gnd'

Steering Servo

  • Servo must be hooked up with black wire innermost (away from LEDs).
  • Also be sure to mount servo on chassis with wire coming out the right side of the car.


  • Camera must be hooked up with black wire towards LEDs on the shield board.
  • Be sure to mount camera on tower with connector down towards the bottom.

Potentiometers (Pots)

  • Pots by default should have arrows pointing toward battery/motor hookup (for demo mods default).

Car Calibration

Serial Terminal

  • Download your favorite Terminal application (I use TeraTerm. Set it for 115200 baud, 8bit, none, 1bit.
  • But first you have to be sure that Windows mbed serial driver has been installed: Windows serial config.



  • You will need to put the car into demo mode 1 and connect up a terminal to the serial port in order to get feedback on the values for your particular servo as hooked up. Then change MAX_STEER_LEFT and MAX_STEER_RIGHT in Spices.cpp with these values to tell the program how your servo is hooked up.

Speed Control

  • This program does not have proper speed control but does modify the speed slightly based on recent error results from the camera. It also modifies the differential speed to each wheel to have better control around curves.
  • While debugging your car you may want to lower the speed. See the constants LIGHT_SPEED and LUDICROUS_SPEED in Spices.cpp. There you can change the speeds used for Modes 4 and 5 above. Range of valid values are 0.4-0.7. Lower is better when debugging the car around the track (mainly to minimize crash forces!).

Strange Gotchas

Glitchy Motors

  • Apparently there is contention between TPM0_CH0 and OpenSDA micro that causes strange issues with Motors (PWM interference). This will cause glitches in motor activty when hooked up to USB only: Found contention

More Info

Sun Apr 20 03:33:03 2014 +0000
Initial version

Who changed what in which revision?

UserRevisionLine numberNew contents of line
redxeth 0:98e98e01a6ce 1